Re: shallow clone not very shallow due to tags

From: Shawn Pearce <spearce@spearce.org>
Date: Aug 15, 2011, 17:16 UTC
Message-ID: <CAJo=hJv_NnZyGnedTQBL_mj3baS8O5Z2wiEbZCvv8305No4ehA@mail.gmail.com>
In-Reply-To: <CACsJy8DF49PJtv41vZEOX0fLg4U1+m6JEW28+iYD6jJxGctEzg@mail.gmail.com>

On Mon, Aug 15, 2011 at 07:03, Nguyen Thai Ngoc Duy <pclouds@gmail.com> wrote:

Show 14 quoted lines

> On Mon, Aug 15, 2011 at 6:58 AM, Shawn Pearce <spearce@spearce.org> wrote:
>> Uhm. That is not a very shallow clone. The clone copied 20234 objects
>> at 9.15 MiB... so its ~20 MiB lighter than a full clone. But nearly
>> all of the tags exist, because the clone client is declaring want
>> lines for them, making the server generate up to 1 commit back from
>> the wanted tag. I know shallow support is the feature nobody wants to
>> think about, but this just seems broken to me. Clients performing a
>> shallow clone shouldn't be asking for tags... but they should be using
>> the include-tag protocol option so that if they do happen to receive a
>> tagged commit, the tag object will also be sent.
>
> The same would apply if the repo in question has many branches. Should
> we fetch only master (or a user-specified set of refs) in shallow
> clone?

Yes, I think a user who is making a shallow clone should only get the HEAD branch to the depth specified, nothing else. If they want additional branches, they should either pass them on the command line to a new flag for clone, or modify their fetch configuration after-the-fact and fetch those separately.

>From what I can gather from some users I have talked to, the primary

usage of shallow clone is to try and (sort of) quickly grab a branch, make a change, and post that change to the maintainers for review and acceptance. E.g. correcting a spelling typo. Relatively simple changes that can be built on a specific branch, and don't really require all of the history.

And if a repository does have more than one branch, but is shallow cloned at say depth of 1, the user probably doesn't get the merge bases between them, so the value of the other branches is greatly reduced. You can't make a merge between these, and a new developer getting involved in the project cannot see how the branches relate to each other. So there isn't a lot of value in sucking down those additional branches during clone.

-- 
Shawn.